Design and analysis for chemical process electrification based on renewable electricity: Coal-to-methanol process as a case study

Abstract

Electrification of traditional large-scale chemical industry based on renewable electricity can greatly reduce process CO2 emission, and store intermittent renewable electricity into chemical products locally to decrease power grid frequency regulation caused by fluctuating renewable electricity. This study presents a framework for electrification of chemical industry from indirect and direct aspects using the state-of-art coal-to-methanol process as a case study. Traditional coal-to-methanol (Process 1) suffers from high CO2 emission due to mismatch of H/C ratio between coal and methanol. A pulverized coal gasification-integrated SOEC process (Process 2) has been investigated, the water–gas-shift unit is avoided and a simplified acid gas removal process is implemented to replace traditional acid gas removal unit in Process 2. Electric heaters and heat pump system are applied in Process 2 as direct electrification methods to form semi-electrified scenario (Process 3). To discuss the effect of electrification levels on process performances, a fully electrified process (Process 4) is also designed. The results show that: CO2 emissions of the four processes are 2.19, 0.71, 0.52 and 0.63 t/t MeOH, and energy efficiency are 57.40 %, 62.32 %, 64.31 % and 57.63 %, respectively. Production costs are 159.1, 294.3, 301.0 and 358.3 $/t MeOH, IRRs are 14, 31, 29 and 14.5 %, respectively. Through this research and analysis, we hope to explore integration potential of renewable electricity and traditional chemical industry, and design a greener methanol production route based on renewable electricity.